Multiple user-multiple-input, multiple-output (MU-MIMO) schemes are drawing more and more attention in recent years in that MU-MIMO may provide both multi-user diversity and spatial diversity. The capacity of MU-MIMO may be much higher than single-user-MIMO (SU-MIMO), especially, for example, if the antenna configuration is asymmetric, for example, in a 4×2 arrangement or a 2×1 arrangement. An asymmetric configuration may occur when a base station (BS) has a greater number of transmit (Tx) antennas than the number of receive (Rx) antennas at the subscriber station (SS), or in a high-correlation channel condition. MU-MIMO differs from SU-MIMO in that MU-MIMO may involve the transmission of transmission streams for multiple users in one transmission function unit.
It will be appreciated that for simplicity and/or clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, if considered appropriate, reference numerals have been repeated among the figures to indicate corresponding and/or analogous elements.